Discussion
Previous studies have shown that the inability of the balloon to cross the wired occlusion accounts for 2%-9% of failed CTO recanalization procedures. The main factors contributing to this scenario include heavy calcification within the CTO lesions and severe coronary tortuosity. To overcome the frustrating situation, several techniques and devices have been invented in recent years. While the effects of these methods have been proven, their availability, complexity, potential risks, and cost have to be taken into consideration in clinical practice. For example, techniques involving the exchange of a more supportive guiding catheter may have a risk of losing the position of the original passed guidewire; the anchor balloon technique requires a proper side branch and has the potential hazard of injuring the side branch; the "child-in-mother" catheter provides more support by deep intubation of the child catheter, which may damage the vessel. In addition, the use of rotational atherectomy is limited by the necessity of recrossing the occlusion with the dedicated and less maneuverable 0.009" stainless-steel RotaWire. This exchange procedure is not always successful if no microcatheter crosses through the lesion. The Tornus device has been proposed as a very effective strategy for the present scenario; however, it must be emphasized that complications such as perforation and procedure-related myocardial infarction may occur as a consequence of Tornus manipulation. Recently, the "wire-cutting" technique has appeared to be a promising approach for facilitating balloon passage. However, the ostium of the coronary artery is likely to be injured by the tip of the guiding catheter during the wire-cutting procedure while pulling back the pressed guidewire.
The initial results of our study indicated that the seesaw balloon-wire cutting technique contributed to an encouraging procedural success rate and might be a useful complement to the methods described above. The new technique is quite different from the wire-cutting technique, which advances a balloon over the original guidewire to press the second guidewire that is withdrawn rapidly and intermittently. With the seesaw balloon-wire cutting technique, two balloons are advanced over two guidewires, respectively, and press both guidewires alternatively to crush the proximal cap of CTOs in multiple positions without pulling back any guidewires. One of the balloons provides extra support, facilitating the other balloon to pass through the CTO lesion. As a result, the seesaw balloon-wire cutting technique avoids the risk of injuring coronary artery ostium, and seems to be safer and more effective than the wire-cutting technique. Moreover, the seesaw balloon-wire cutting technique involves only conventional wires and balloons, so it has the advantages of easy operation, low cost, and decreased fluoroscopy time. Passing the second guidewire is a prerequisite for the seesaw balloon-wire cutting technique. In order to ensure the high success rate of this novel technique, some key points need to be highlighted. First, hydrophilic-coated and stiffer wires should be selected as the second guidewire due to the reduced resistance and good maneuverability. However, the operators have to avoid advancing the second guidewire into subintimal space to prevent the subsequent dissection. Second, microcatheters were used to improve the second guidewire maneuverability in most cases, which may be helpful in increasing the success rate of passing the second wire. Third, short and low-profile balloons are recommended and they should be inflated with high pressure (≥18 atm) to press the buddy guidewire to cut the proximal cap of CTOs in different positions. In terms of safety, no serious complications were observed in the present study.
Transradial PCI for CTOs has gained progressive acceptance in the last few years and growing evidence has demonstrated its benefits of earlier ambulation, shorter hospital stay, lower medical cost, fewer access-site complications, and patient preference. In the present study, most CTO PCIs were performed by transradial approach. A disadvantage of the transradial approach is the weak backup support of guiding catheters. The seesaw balloon-wire cutting technique dramatically improves the backup support of guiding catheters and should be more suitable for transradial PCI of CTOs. However, there is an anatomy requirement for the technique. For ostial occluded lesions, the technique may be less effective. The reason is attributed to the mechanism of the technique. With this novel technique, the two balloons are progressed alternatively and one of the balloons provides extra backup for facilitating the other balloon to cross the CTO. Therefore, a certain distance from the occlusion to the ostium is needed. The major cause of failure in the seesaw balloon-wire cutting technique is the heavy circular calcification within the CTO lesion, which can be dealt with via use of a Rotablator.
Study Limitations
The present study enrolled only a small number of patients, and the seesaw balloon-wire cutting technique was not compared with other conventional methods, such as Tornus catheter and rotational atherectomy. Therefore, the efficacy and safety of this novel technique need to be further confirmed in future studies.